Bugfix maxHeight after $.colorbox.resize()

Earlier, if I set .colorbox{maxHeight:'95%'...} then colorbox frame gets vertical scrollbar (if content is heighter than frame) but if then I do $.colorbox.resize() my colorbox frame becomes heighter than wrapper page and my maxHeight option is ignored, so this is bugfix for it.
Wouldn't following code be more explicit:

```js
settings.h = Math.max(settings.h, settings.mh);
```